Apparatus and method for controlling an occupancy ratio of each region in a buffer

ABSTRACT

A buffer control device included in a base station apparatus acquires predetermined information regarding data communication between the base station apparatus and external apparatuses other than the base station apparatus. The buffer control device predicts an amount of traffic in the data communication based on the acquired predetermined information, and controls an occupation ratio of each of regions that are arranged in a buffer in association with a plurality of priorities, based on the amount of traffic in the predicted data communication, where the buffer stores pieces of data each of which is assigned one of the plurality of priorities and transmitted within the base station apparatus from a first processing unit to a second processing unit via a high speed serial interface.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based upon and claims the benefit of priority fromthe prior Japanese Patent Application No. 2013-171769 filed on Aug. 21,2013, the entire contents of which are incorporated herein by reference.

FIELD

Exemplary embodiments of the present disclosure are related to apparatusand method for controlling an occupancy ratio of each region in abuffer.

BACKGROUND

A high speed serial interface such as SRIO (Serial Rapid IO) is known asa technology which connects devices with each other. For example, SRIOis also used in a processing unit such as a baseband processing unitwhich performs a signal processing for wireless signal in a base stationof a wireless communication system. Respective processing modules withinthe baseband processing unit are connected with each other in a starshape using a SRIO switch, and transmit and receive data through a datacommunication path of a SRIO packet.

A receiver-side flow control is generally used for a flow control inSRIO communication and thus, a flow control buffer is provided on atransmission side. The space of the buffer for transmission is fixedlydivided into regions to be allocated for respective “High”, “Mid”, and“Low”, each of which is a priority of SRIO packets.

The SRIO switch sequentially stores SRIO packets in the region of aretransmission buffer corresponding to the priority of each SRIO packetin an order that the SRIO packets are received from each processingunit. Also, the SRIO switch reads SRIO packets from the region for“High” SRIO packets having the highest priority and transmits the SRIOpacket to a destination. Subsequently, when the packet transmission ofthe region for the “High” SRIO packet is completed, the SRIO switchreads SRIO packets from a region for “Mid” SRIO packets having the nexthighest priority and transmits the SRIO packets to the destination.Thereafter, when the packet transmission of the region for the “Mid”SRIO packet is completed, the SRIO switch reads SRIO packets from aregion for “Low” SRIO packets and transmits the SRIO packets to thedestination.

See, for example, Japanese Patent Application Laid-Open No. 2010-218108and Japanese Patent Application Laid-Open No. 2006-113798.

SUMMARY

A buffer control device according to one aspect of the presentdisclosure includes an acquisition unit which acquires predeterminedinformation regarding data communication between a base stationapparatus and external apparatuses other than the base stationapparatus. The buffer control device predicts an amount of traffic inthe data communication based on the acquired predetermined information.The buffer control device controls an occupation ratio of each ofregions that are arranged in a buffer in association with a plurality ofpriorities, based on the predicted amount of traffic in the datacommunication, where the buffer stores pieces of data each of which isassigned one of the plurality of priorities and transmitted within thebase station apparatus from a first processing unit to a secondprocessing unit via a high speed serial interface.

The object and advantages of the invention will be realized and attainedby means of the elements and combinations particularly pointed out inthe claims. It is to be understood that both the foregoing generaldescription and the following detailed description are exemplary andexplanatory and are not restrictive of the invention, as claimed.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating an example of an overall configurationof a wireless communication system, according to an embodiment.

FIG. 2 is a diagram illustrating an example of a configuration of a basestation apparatus, according to an embodiment.

FIG. 3 is a diagram illustrating an example of a configuration of a BBunit of the base station apparatus, according to an embodiment.

FIG. 4 is a diagram illustrating an example of a functionalconfiguration of a SRIO switch, according to an embodiment.

FIG. 5 is a diagram illustrating an example of information stored in aweight table, according to an embodiment.

FIG. 6 is a diagram illustrating an example of change in buffercapacity, according to an embodiment.

FIG. 7 is a diagram illustrating an example of an operational flowchartfor entire process executed by the SRIO switch, according to anembodiment.

FIG. 8 is a diagram illustrating an example of an operational flowchartfor a process of adjusting a buffer amount, according to an embodiment.

FIG. 9 is a diagram illustrating an example of an operational flowchartfor a process of storing a packet into a buffer, according to anembodiment.

FIG. 10 is a diagram illustrating an example of an operational sequencefor a random access procedure at the time of originating a call,according to an embodiment.

FIG. 11 is a diagram illustrating an example of change in the number ofuser terminals requesting data communication, according to anembodiment.

FIG. 12 is a diagram illustrating an example of a process ofretransmitting downstream data, according to an embodiment.

FIG. 13 is a diagram illustrating an example of change in aretransmission amount of downstream data, according to an embodiment.

FIG. 14 is a diagram illustrating an example of buffer control,according to an embodiment.

DESCRIPTION OF EMBODIMENTS

There is a problem that congestion occurs in the SRIO switch and thus,the communication speed is reduced in the technique described above.

For example, when a large number of SRIO packets having the “High”priority occur, the region for the “High” priority packets overflows andthe SRIO packets stay in the SRIO switch. Therefore, a transmissiondelay or transmission error occurs and thus, the communication speed isreduced.

Hereinafter, descriptions will be made on exemplary embodiments of thebuffer control device, the buffer control method and the base stationapparatus disclosed in the present disclosure with reference toaccompanying drawings. Further, the present disclosure is not limited tothe exemplary embodiments.

Embodiment 1

[System Configuration]

FIG. 1 is a diagram illustrating an example of an overall configurationof a wireless communication system, according to an embodiment. Asillustrated in FIG. 1, the wireless communication system includes aplurality of user terminals 1 and a base station apparatus 10.

Each user terminal 1 is a terminal device which performs a wirelesscommunication with other user terminal 1 through the base stationapparatus 10, and transmits and receives various control information toand from the base station apparatus 10. For example, the user terminal 1is a portable phone, a smart phone, or a personal computer.

The base station apparatus 10 is an apparatus which performs variouscontrol regarding the wireless communication of the user terminal 1. Forexample, the base station apparatus 10 relays wireless communicationbetween different user terminals 1, transmits various controlinformation to the user terminals 1 and controls, for example, thehandover of the user terminals 1.

[Hardware Configuration]

FIG. 2 is a diagram illustrating an example of a configuration of a basestation apparatus, according to an embodiment. As illustrated in FIG. 2,the base station apparatus 10 includes a plurality of AMP units 11, aplurality of TRX units 12, a BB unit 13, and a CNT unit 14. Further, thebase station apparatus 10 may include processing units other than theprocessing units illustrated.

Each AMP unit 11 is a processing unit which performs power amplificationon the wireless signal transmitted and received through an antennacoupled to each AMP unit 11. For example, each AMP unit 11 isimplemented by, for example, an amplification circuit.

Each TRX unit 12 is a processing unit which performs analog to digitalconversion or digital to analog conversion on the wireless signal. Forexample, each TRX unit 12 is implemented by, for example, a conversioncircuit.

The BB unit 13 is a processing unit which performs a signal processingsuch as a base band processing, on the wireless signal. For example, theBB unit 13 is implemented by, for example, a DSP (Digital SignalProcessor) or LSI. The processing units such as respective circuits areconnected with each other via the SRIO in the BB unit 13.

The CNT unit 14 is a processing unit which performs, for example, an IP(Internet Protocol) layer protocol processing, call control processing,OAM (Operations Administration and Maintenance) processing, band controlprocessing, collecting of a fault information, and monitoring of adevice fault. For example, the CNT unit 14 is implemented by, forexample, a CPU (Central Processing Unit) and the DSP.

[Hardware Configuration of BB Unit]

FIG. 3 is a diagram illustrating a configuration example of a BB unit ofa base station apparatus, according to an embodiment. As illustrated inFIG. 3, the BB unit 13 includes a LSI (Large Scale Integration) 13 a,DSP #01 to DSP #06, and a SRIO switch 20, and respective processingunits are connected with each other in a star shape centering on theSRIO switch 20.

The LSI 13 a transmits and receives data between interfaces such as a RF(Radio Frequency) interface and a core network interface. Further, theLSI 13 a transmits and receives data to and from the TRX unit 12. TheLSI 13 a communicates with each DSP through the SRIO switch 20.

Each DSP uses one or a plurality of DSPs to cause various processingunits to be performed. Here, the processing units to be performedincludes, for example, a layer 2 processing unit, an encoding unit, amodulating unit, a demodulating unit, a decoding unit, and a scheduler.

The layer 2 processing unit is a processing unit which performsprocessing for interfacing with the CNT unit 14 and performs variousprocessing regarding layer 2. The processing performed in layer 2includes processing regarding respective sub-layers, such as MAC (MediaAccess Control), RLC (Radio Link Control), and PDCP (Packet DataConvergence Protocol).

The encoding unit performs an encoding process, such as a turboencoding, on data from the layer 2 processing unit. The modulating unitperforms, on data from the encoding unit, a modulating process or aprocess for wireless transmission. The demodulating unit performs ademodulating process for data from the LSI 13 a and a channel estimationprocess. The decoding unit performs a decoding process, such as a turbodecoding, on data from de-multiplexing unit. The scheduler performs awireless bandwidth control or collecting of measured information.

The SRIO switch 20 is connected with each processing unit within the BBunit 13 via the SRIO to relay data communications within the BB unit 13using the SRIO. For example, a buffer for transmission is installed atthe transmission side in the SRIO switch 20 for each of priorities ofthe SRIO packet: “High”, “Mid”, and “Low”.

Also, the SRIO switch 20 sequentially stores the SRIO packet in thecorresponding region of a retransmission buffer corresponding to thepriority of each SRIO packet, in an order that the SRIO packets arereceived from each processing unit. Also, the SRIO switch sequentiallyreads a SRIO packet from a region for the “High” priority which is thehighest priority and transmits the SRIO packet to a destination.

[Configuration of SRIO Switch]

FIG. 4 is a diagram illustrating an example of a functionalconfiguration of a SRIO switch, according to an embodiment. Asillustrated in FIG. 4, the SRIO switch 20 includes a plurality ofreception buffers 20 a, a flow control buffer group 21, a transmissioncontrol unit 22, a buffer adjustment unit 23, and a packet control unit24.

Each reception buffer 20 a is a buffer provided for each processing unitconnected with the SRIO switch 20. For example, the encoding unitperformed by DSP #01 writes, into the reception buffer 20 a, the SRIOpacket that is to be transmitted to the conversion unit performed by theDSP #02.

The flow control buffer group 21 maintains packets in buffers each ofwhich is provided for each priority which is set for the SRIO packet.For example, the flow control buffer group 21 includes a buffer 21 a fora “High” priority, a buffer 21 b for a “Mid” priority, and a buffer 21 cfor a “Low” priority, and temporarily maintains the SRIO packet that isto be transmitted from a processing unit to the other processing unit inthe BB unit 13.

The buffer 21 a for the “High” priority maintains the SRIO packet forwhich the highest priority of “High” is set. The buffer 21 b for the“Mid” priority maintains the SRIO packet for which the next highestpriority of “Mid” is set. The buffer 21 c for the “Low” prioritymaintains the SRIO packet for which the lowest priority of “Low” is set.

The transmission control unit 22 is a processing unit which reads a SRIOpacket from the flow control buffer group 21 and transmits the SRIOpacket to the processing unit of the destination. For example, thetransmission control unit 22 reads a SRIO packet from the buffer 21 afor the “High” priority to transmit the SRIO packet to the destination.Subsequently, when transmission of the packets stored in the buffer 21 afor the “High” priority is completed, the transmission control unit 22reads a SRIO packet from the buffer 21 b for the “Mid” priority totransmit the SRIO packet to the destination. Thereafter, whentransmission of the packets stored in the buffer 21 b for the “Mid”priority packet is completed, the transmission control unit 22 reads aSRIO packet from the buffer 21 c for the “Low” priority to transmit theSRIO packet to the destination.

Further, the transmission control unit 22 also performs a retransmissioncontrol of a SRIO packet. Specifically, the transmission control unit 22performs the retransmission control when a transmission error occurs ora retransmission request is received from the processing unit of thereception side. For example, the transmission control unit 22 instructsthe packet control unit 24 to store SRIO packets subsequent to the SRIOpacket for which a transmission error has been occurred, and performsthe retransmission of the SRIO packets.

The buffer adjustment unit 23 is a processing unit which predicts theamount of traffic for SRIO packets based on a parameter acquired in thebase station apparatus 10 and dynamically controls a buffer amount,which is allocated for each priority, of a buffer included in the SRIOswitch 20 based on the predicted value. The buffer adjustment unit 23includes a weight table 23 a, a parameter collection unit 23 b, aparameter analysis unit 23 c, and a capacity control unit 23 d.

The weight table 23 a stores a weight which is set for each parameteracquired in the base station apparatus 10. FIG. 5 is a diagramillustrating an example of information stored in a weight table,according to an embodiment. As illustrated in FIG. 5, the weight table23 a stores “number”, “parameter factor and information”, “weightingfactor 1”, and “weighting factor 2”, in association with each other.

Here, the “number” to be stored is a number which indicates a prioritylevel of the weighting factor 1. The “parameter factor and information”is information which specifies the parameter acquired in the basestation apparatus 10. The “weighting factor 1” is information on weightset for the parameter and is used when controlling the buffer using thetotal weight. The “weighting factor 2” is information on weight set forthe parameter and is used when separately controlling each of buffers.

In the example of FIG. 5, the number “10” and “1.5” are set for “thenumber of UEs (user terminals) that requests data communication” as theweighting factor 1 and the weighting factor 2, respectively. Further,the number “4” and “1.8” are set for the “data amount to be subjected toHO (handover)” as the weighting factor 1 and the weighting factor 2,respectively.

Further, any one of the priorities corresponds with each “parameterfactor and information”. For example, the weighting factor 1 and theweighting factor 2 for the “number” field having a value of 1 (one) andthe “parameter factor and information” field having the content of“number of UEs requesting data communication” are weights given for the“High” priority. Further, the weighting factor 1 and the weightingfactor 2 for the “number” field having a value of 2 (two) and the“parameter factor and information” field having the content of “whetherUE currently performing the data communication exists and retransmissionamount” are weights given for the “Mid” priority. Such a weight factorsetting may be arbitrarily performed by a managing operator inaccordance with the system.

The parameter collection unit 23 b is a processing unit which collectsparameters regarding the data communication between the base stationapparatus 10 and an external apparatus other than the base stationapparatus. For example, the parameter collection unit 23 b collectsrespective parameters illustrated in FIG. 5 from each processing unitthat is connected with the SRIO switch 20 via a dedicated line, andoutputs the collected results to the parameter analysis unit 23 c. Inthe case, the collection timing may be set arbitrarily, for example, atregular time intervals or at the timing designated by the managingoperator.

The parameter analysis unit 23 c is a processing unit which predicts theamount of traffic of the data communication between the base stationapparatus 10 and an external apparatus other than the base stationapparatus 10, based on the parameters collected by the parametercollection unit 23 b. An example for which the weighting factor 1illustrated in FIG. 5 is used will be described. The parameter analysisunit 23 c refers to the weighting factor 1 of the weight table 23 a tospecify weight for each parameter collected by the parameter collectionunit 23 b.

Also, the parameter analysis unit 23 c calculates the total weight ofthe weighting factors 1 for each of priorities: “High”, “Mid”, and“Low”. Thereafter, the parameter analysis unit 23 c calculates a ratioor relative value of each priority from the calculated total weights ofweighting factors for the respective priorities. For example, when thetotal weight for the “High” priority is 50 (fifty), the total weight forthe “Mid” priority is 20 (twenty), and the total weight for the “Low”priority is 30 (thirty), the parameter analysis unit 23 c determinesthat the ratio of priorities is “High:Mid:Low=5:2:3”. Also, theparameter analysis unit 23 c outputs, for example, the calculated ratioto the capacity control unit 23 d.

The capacity control unit 23 d is a processing unit which controls acapacity of each buffer of the flow control buffer group 21. Forexample, the capacity control unit 23 d adjusts the buffer capacity tobe allocated for each buffer within the entire capacity of the flowcontrol buffer group 21, based on the information notified from theparameter analysis unit 23 c.

For example, in the case of using the weighting factor, the capacitycontrol unit 23 d receives information of “High:Mid:Low=5:2:3” from theparameter analysis unit 23 c in a state where the entire capacity of theflow control buffer group 21 is “500 MB (megabyte)”. In this case, thecapacity control unit 23 d adjusts the capacity of the buffer 21 a forthe “High” priority to become “500×5/10=250 MB”. Similarly, the capacitycontrol unit 23 d adjusts the capacity of the buffer 21 b for the “Mid”priority and the capacity of the buffer 21 c for the “Low” priority tobecome “500×2/10=100 MB” and “500×3/10=150 MB”, respectively.

Here, a method which changes an address of each buffer for storing theSRIO packet may be used as an adjustment method. For example, thecapacity control unit 23 d rewrites a start address and an end addressinto the address table 24 a according to the adjusted capacity to adjustthe buffer amount of each buffer allocated for each priority.

FIG. 6 is a diagram illustrating an example of a change in buffercapacity, according to an embodiment. As illustrated in FIG. 6, thecapacity control unit 23 d adjust the buffer capacity of each buffer foreach priority, by changing the ratio of the buffer capacity to beallocated to each buffer for each priority without changing the totalcapacity of the entire buffer. The example of FIG. 6 illustrates anexample in which the capacity control unit 23 d makes the ratio ofbuffer 21 a for the “High” priority larger and does not change the ratioof buffer 21 b for the “Mid” priority, and makes the ratio of buffer 21b for the “Low” priority smaller.

Further, the capacity control unit 23 d may compare the buffer capacityafter adjustment with the current buffer capacity in order to calculatean increase/decrease value of each priority, and adjust the bufferamount of each buffer for each priority based on the calculatedincrease/decrease value.

The packet control unit 24 includes an address table 24 a, a storageaddress calculation unit 24 b, an interface unit 24 c, and aretransmission processing unit 24 d, and is a processing unit whichcontrols the packet transmission using these components.

The address table 24 a is a table which stores an address of the flowcontrol buffer group 21 for storing SRIO packets. For example, theaddress table 24 a stores start and end addresses of each buffer inassociation with the each buffer. Here, the information stored in theaddress table is rewritten by the capacity control unit 23 d.

The storage address calculation unit 24 b is a processing unit whichcalculates, for each reception buffer 20 a, the address of the flowcontrol buffer corresponding to the priority set for the received SRIOpacket, at which the SRIO packet is to be stored, based on the addresstable 24 a. The storage address calculation unit 24 b outputs thecalculated address information and the received SRIO packet to theinterface unit 24 c.

The interface unit 24 c is a processing unit which stores the receivedSRIO packet in a designated location of the buffer corresponding to adesignated priority. For example, the interface unit 24 c stores thereceived SRIO packet using the address of the flow control buffer groupfor storing the SRIO packet, received from the storage addresscalculation unit 24 b.

For example, when an address of “0x0012” is designated from the storageaddress calculation unit 24 b, the interface unit 24 c write thereceived SRIO packet into the flow control buffer by designating theaddress “0x0012” for the flow control buffer group 21. As a result, theinterface unit 24 c may store the SRIO packet in a region of the buffercorresponding to the priority designated for the SRIO packet.

The retransmission processing unit 24 d is a processing unit whichperforms retransmission of a SRIO packet. For example, when aretransmission request for the SRIO packet after the SRIO packet forwhich the transmission error has been occurred is received from thetransmission control unit 22, the retransmission processing unit 24 dperforms the retransmission of SRIO packets subsequent to the SRIOpacket for which the retransmission is requested.

[Process Flow]

Next, an operational flowchart for processes performed by the SRIOswitch 20 will be described. Here, overall process flow, a buffer amountadjustment process, and a process for storing the SRIO packet into thebuffer will be described.

(Overall process)

FIG. 7 is a diagram illustrating an operational flowchart for entireprocess executed by a SRIO switch, according to an embodiment. Asillustrated in FIG. 7, when power is turned ON, the SRIO switch 20activates the buffer amount adjustment function (S101) and performsinitialization (S102).

Thereafter, when a parameter collection timing arrives (“YES” at S103),the parameter collection unit 23 b collects parameters (S104).Subsequently, the parameter analysis unit 23 c refers to the weighttable 23 a to place weight on the collected parameter (S105).

Also, the parameter analysis unit 23 c performs a parameterdetermination process which calculates, for example, weight on eachpriority or a ratio of each priority using the weighting factor 1 orweighting factor 2 of the parameter (S106). Thereafter, when theparameter corresponding to each priority is equal to or greater than athreshold value serving as a reference value for determining whether abuffer capacity is required to be changed (“YES” at S107), the capacitycontrol unit 23 d changes the buffer capacity for the correspondingpriority (S108). Further, when the parameter corresponding to eachpriority is less than the threshold value serving as the reference valuefor determining whether the buffer capacity is required to be changed(“NO” at S107), the capacity control unit 23 d ends the process.

(Adjustment Process)

FIG. 8 is a diagram illustrating an example of an operational flowchartfor an adjusting process of a buffer amount, according to an embodiment.As illustrated in FIG. 8, the capacity control unit 23 d determineswhether an adjustment amount is a positive value, negative value, orzero for each priority using a parameter or weight analysis result bythe parameter analysis unit 23 c (S201).

When it is determined that the adjustment amount is a positive value(“PLUS” at S201), the capacity control unit 23 d determines whether thecurrent buffer amount of all the flow control buffer group 21 is themaximum value (Max) (S202). When it is determined that the currentbuffer amount of all the flow control buffer group 21 is not the Maxvalue (“NO” at S202), the capacity control unit 23 d updates the addressfor storing the SRIO packet stored in the address table 24 a so as toincrease the buffer amount according to the adjustment amount (S203).Further, when the adjustment amount is a positive value (“PLUS” at S201)and it is determined that the current buffer amount is the Max value(“YES” at S202), the capacity control unit 23 d ends the process.

In the meantime, when it is determined that the adjustment amount is anegative value (“MINUS” at S201), the capacity control unit 23 ddetermines whether the current buffer amount of all flow control buffergroup 21 is zero (S204). When it is determined that the current bufferamount of all the flow control buffer group 21 is not zero (“NO” atS204), the capacity control unit 23 d updates an address for storing theSRIO packet stored in the address table 24 a so as to decrease thebuffer amount according to the adjustment amount (S205). Further, whenthe adjustment amount is the negative value (“MINUS” at S201) and it isdetermined that the current buffer amount is zero (“0” at S201), thecapacity control unit 23 d ends the process.

(Storing Process)

FIG. 9 is s diagram illustrating an example of an operational flowchartfor storing a packet into a buffer, according to an embodiment. Asillustrated in FIG. 9, when the SRIO packet is received (S301), thestorage address calculation unit 24 b detects the priority of thereceived packet (S302).

Subsequently, the storage address calculation unit 24 b refers to theaddress table 24 a to acquire the latest address location correspondingto the detected priority (S303) and further, acquires an addresslocation when the buffer reaches its maximum size (S304).

Thereafter, the storage address calculation unit 24 b calculates thelocation for storing the received SRIO packet in a range spanning fromthe latest location to the maximum address location (S305). Theinterface unit 24 c stores the received SRIO packet into the calculatedlocation for storing the SRIO packet (S306).

Specific Example

Next, a specific example in which the buffer capacity is changed usingthe parameter is described. Here, as an example, the buffer controlillustrated in FIG. 5 using “the number of user terminals that requestdata communication”, the buffer control using the “retransmission amountof the downstream data” and an example of performing change of buffercapacity using the weighting factor 2 of FIG. 5 will be described.

(Calculation of Number of User Terminals)

First, an example of extracting the number of user terminals whichrequest data communication as the parameter will be described. When theuser terminal 1 establishes connection or performs resynchronizationwith the base station apparatus 10 by, for example, originating a callor handover, a random access procedure is performed. In the randomaccess procedure, a channel used at first for transmitting a preamble iscalled a Physical Random Access Channel (PRACH).

FIG. 10 is a diagram illustrating an example of a random accessprocedure at the time of originating a call, according to an embodiment.The user terminal 1 transmits a preamble, which is selected randomlyfrom a plurality of preambles prepared in a cell, as message 1 (S401).When the preamble is detected, the base station apparatus 10 transmitsRACH response, which is acknowledgement information, as message 2(S402).

The user terminal 1 which has received the RACH response transmits RRC(Radio Resource Control) connection request, which is a connectionrequest signal, as message 3 (S403). The base station apparatus 10transmits RRC connection setup, which contains cell setting informationfor establishing a connection, as message 4 after receiving message 3(S404). Thereafter, when an UE ID of the user terminal 1 is included inmessage 4, the user terminal 1 completes the random access procedure toestablish a connection (S405).

The parameter collection unit 23 b of the base station apparatus 10monitors the number of connections, which is established using message 4of the random access procedure performed at the time of originating acall, for example, every 10 ms. Also, the number of user terminals thatrequest the data communication is calculated by, for example, ascheduler (not illustrated) and transmitted to the buffer adjustmentunit 23. Monitoring of the number of established connections and thenumber of user terminals will be described with reference to FIG. 11.

FIG. 11 is a diagram illustrating an example of a change in the numberof user terminals that request data communication, according to anembodiment. FIG. 11 is a graph illustrating the result of monitoring thenumber of connections established using message 4 for every 10 msinterval. The numeral “a” of FIG. 11 indicates the number of messages 4explained with reference to FIG. 10 and the numeral “b” of FIG. 11indicates the number of user terminals that request the datacommunication. The parameter collection unit 23 b of the bufferadjustment unit 23 monitors the received “number of user terminals thatrequest data communication”. Also, for example, when the number of userterminals exceeds a threshold value (e.g., 150), the parameter analysisunit 23 c places weight on the parameter.

As described above, the base station apparatus 10 accepts 10 userterminals in average in the RACH procedure operated at every 10 msinterval. Accordingly, in a case where the number of user terminalsreaches 150, for example, when the maximum number of user terminalswithin a coverage cell is set as 600, the number of user terminalsexceeds about 25% of the maximum number “600”. Therefore, it may beassumed that control information within the BB unit 13 increases and thenumber of SRIO packets having “High” priority increases.

(Calculation of Retransmission Amount)

Next, an example of extracting the retransmission amount of downstreamdata as a parameter will be described. FIG. 12 is a diagram illustratingan example of a retransmitting process of downstream data, according toan embodiment. As illustrated in FIG. 12, the base station apparatus 10transmits the downstream transmission data to the user terminal 1 in adownlink data channel.

The user terminal 1 transmits information as to whether data to bereceived is arrived, to the base station apparatus 10, using ACK/NACKinformation transmitted in a uplink control channel. When the NACKindicating that the data to be received is not arrived is received, thebase station apparatus 10 retransmits the downstream data to the userterminal 1 which is a NACK transmission source.

Here, the scheduler within the BB unit 13 may calculate theretransmission amount of the user terminal which is performing datacommunication, based on the ACK/NACK information extracted from theuplink control channel at the encoding unit within the BB unit 13. FIG.13 is a diagram illustrating change of the retransmission amount of thedownstream data.

FIG. 13 is a diagram illustrating an example of change in the number ofretransmission bits measured by counting the number of bitsretransmitted at an interval of 8 (eight) milliseconds. As illustratedin FIG. 13, the number of retransmission bits is increasing as timeelapses. Also, the number of retransmission bits increases continuouslyuntil the time reaches 56 milliseconds and exceeds the threshold valueafter 56 milliseconds. As described above, while a state of exceedingthe threshold value 600 Kbits is continued, parameters are collected bythe parameter collection unit 23 b and a determination is made byplacing weight on the parameters. Since the retransmission is performedevery 8 (eight) milliseconds, the threshold value may be regarded as “75Kbits×8 (milliseconds)=600 Kbits” which corresponds to a value for acase where 75 Kbits, which are 50% of 150 Kbits which are the maximumnumber of transmission bits, are retransmitted in the duration of 1(one) millisecond. Since data to be transmitted increases when theretransmission amount of the user terminals performing datacommunication is increased, it may be assumed that the number of SRIOpackets having the priority of “Mid” also increases.

(Buffer Control)

The parameter collection unit 23 b collects the number of user terminalsthat request the data communication and the retransmission amount ofdownstream data, as illustrated in FIG. 11 or FIG. 13. In theembodiment, a ratio of the number of user terminals requesting the datacommunication to the threshold value of “150” is 26% or more, and aratio of the value “138 Kbits”, which is the average value of the numberof retransmission bits exceeding the threshold value of “600”, to thethreshold value of “600” is 23% or more.

Here, as an example, since control information used for “the number ofuser terminals requesting data communication” is a direct factor ofincreasing the number of packets having the “High” priority, theparameter analysis unit 23 c refers to the field of weighting factor 2of FIG. 5 to acquire “1.5” as the weighting factor 2. Then, theparameter analysis unit 23 c multiplies 26% by 1.5 using the weightingfactor 2 of “1.5”, thereby obtaining “0.4≈(0.26×1.5)”.

Further, since the “retransmission amount of downstream data” becomes adirect factor of increasing the amount of data in an individual channel,the parameter analysis unit 23 c refers to the field of weighting factor2 of FIG. 5 to acquire “1.5” as the weighting factor 2. Then, theparameter analysis unit 23 c multiplies 23% by 1.5 times using theweighting factor 2 of “1.5”, thereby obtaining “0.3≈(0.23×1.5)”.

Further, as an example, it is assumed that the entire capacity of thebuffer is 9 Kbytes, and 3 Kbytes is allocated to each region of thebuffers for the “High”, “Mid”, and “Low” priorities. Then, since “thenumber of user terminals requesting data communication” affects the“High” priority, the parameter analysis unit 23 c calculates “3Kbytes×(1.0+0.4)=4.2 Kbytes” as the capacity of the buffer 21 a for the“High” priority.

Further, since “the retransmission amount of downstream data” affectsthe “Mid” priority, the parameter analysis unit 23 c calculates “3Kbyte×(1.0+0.3)=3.9 Kbytes” as the capacity of the buffer 21 b for the“Mid” priority.

Also, the parameter analysis unit 23 c calculates “9.0−4.2−3.9=0.9Kbyte” as the capacity of the buffer 21 c for the “Low” priority.

The capacity control unit 23 d updates the address table 24 a by usingthe calculation results. FIG. 14 is a diagram illustrating an example ofbuffer control, according to an embodiment. As illustrated in FIG. 14,before adjustment of the buffer capacity, a region of “0x0000-0x0BB4”corresponds to the buffer 21 a for the “High” priority, a region of“0x0BB8-0x176C” corresponds to the buffer 21 b for the “Mid” priority,and a region of “0x1770-lowest address” corresponds to the buffer 21 cfor the “Low” priority.

In this state, with respect to the buffer 21 a for the “High” priority,the capacity control unit 23 d increases the capacity of the buffer 21 afor the “High” priority to 4.2 Kbytes by rewriting the address table 24a so that the highest address-the lowest address for the “High” priorityis changed from “0x0000-0x0BB4” into “0x0000-0x1064”.

Similarly, with respect to the buffer 21 b for the “Mid” priority, thecapacity control unit 23 d rewrites the address table 24 a so that thehighest address-the lowest address for the “Mid” priority is changedfrom “0x0BB8-0x176C” into “0x1068-0x1FA0”, thereby increasing thecapacity of the buffer 21 b for the “Mid” priority to 3.9 Kbytes.

Further, with respect to the buffer 21 c for the “Low” priority, thecapacity control unit 23 d rewrites the address table 24 a so that thestart location is changed from “0x1770” to “0x1FA4”, thereby decreasingthe capacity of the buffer 21 c for the “Low” priority to 0.9 Kbyte. Ina way described above, the capacity control unit 23 d dynamicallychanges each buffer capacity using various parameters without changingthe total capacity of respective buffers.

Conventionally, the flow control buffer within the SRIO switch 20determines the buffer amount systematically. The flow control bufferdivides a single buffer into regions corresponding to respectivepriorities, and determines a buffer amount for each priority so that thebuffer amount takes a value between the average value and the maximumvalue of an amount of data transfer. Therefore, a larger size of bufferhas been prepared for each priority.

However, there are few cases where the used amounts of respectivebuffers for “High” and “Mid” priorities become the maximum values at onetime. Further, even when the used amounts of the respective buffers for“High” and “Mid” priorities become the maximum values at one time due toutilization of the scheme of the embodiment, the capacity of the buffer21 c for the “Low” priority may be made smaller, thereby allowing theSRIO packet having the “High” priority to be preferentially transmitted.Therefore, a buffer space for each priority may be efficiently used andthus the entire buffer amount may be reduced to achieve cost reduction.

Conventionally, when retransmission request occurs, data areretransmitted and the power consumption is increased. However, with thescheme of the embodiment, the ratio of the amount of the flow controlbuffer to be used for each priority to the total amount of the flowcontrol buffer may be changed depending on the traffic amount.Therefore, the occurrence of retransmission processing may be reducedand the power consumption may be reduced accordingly.

Conventionally, since the internal operation timing of the BB unit 13 isprescribed by taking into account the occurrence of retransmission,timings including an operating margin are set for respective processingunits. However, the scheme of the embodiment allows the ratio ofoccurrence of retransmission to be lowered, thereby reducing theoperating margin. Therefore, an enough processing time is allowed andperformance of the BB unit 13 is improved, thereby increasing the numberof users available for data communication.

Embodiment 2

While the embodiment of the present disclosure has been described, thepresent disclosure may be practiced in various shapes in addition to theembodiment described above. Therefore, other embodiments will bedescribed below.

(Buffer Adjustment Unit)

In Embodiment 1, an example in which the buffer adjustment unit 23 isequipped in the SRIO switch 20 is described, but the present disclosureis not limited thereto. For example, the buffer adjustment unit 23 maybe installed outside of the SRIO switch 20. In this case, the bufferadjustment unit 23 is implemented by, for example, a DSP connected withthe SRIO switch 20.

(Retransmission Control)

For example, it is assumed that, in a case where each buffer capacity isfixed, a large number of the SRIO packets having the “High” priority aregenerated ant a buffer overflow has been occurred. In this case,retransmissions of the SRIO packets occur and the SRIO packets to beretransmitted are accumulated in the SRIO switch. Therefore, the SRIOpackets having the “High” priority generated successively stay in theSRIO switch without being transmitted. As a result, the SRIO switchfails to exhibit inherent performance and the communication speed isreduced. Further, power consumption also increases as the occurrence ofretransmission increases.

According to the embodiment, it is possible to detect increase in thenumber of the SRIO packets having the “High” priority and to increasethe buffer capacity for the “High” priority. Therefore, the occurrenceof buffer overflow as well as retransmission of packets may besuppressed. Further, suppression of retransmission allows suppression ofpower consumption.

(System)

Further, some or all of processes described as being automaticallyperformed among respective processes described in the embodiment may bemanually performed. Meanwhile, some or all of processes described asbeing manually performed among the respective processes may beautomatically performed using a known method. In addition, informationincluding a processing sequence, control sequence, specific name,various data or parameters illustrated in the specification oraccompanying drawings may be arbitrarily changed unless otherwise noted.

Further, each component of each device illustrated is a functional andconceptual device and does not necessarily need to be configured inaccordance with a physical configuration as illustrated. That is, aspecific shape of distribution or integration of respective devices isnot limited to a shape illustrated. That is, some or all of devices maybe configured by being functionally and physically distributed orintegrated in any basic functional unit depending on, for example,various load or use situations. Further, some or all of respectiveprocessing functions performed by respective devices may be implementedby a CPU or program analyzed and executed by the CPU, or hardwareconfigured by wired-logic.

As an example, the base station apparatus 10 stores the buffer controlprogram, which performs various processing of the transmission controlunit 22, the buffer adjustment unit 23, and the packet control unit 24,in a ROM (Read Only Memory) and reads out, from the ROM, the buffercontrol program so as to be executed by, for example, the CPU. Also, thebase station apparatus 10 may cause the buffer control process toperform a control similar to that performed by the transmission controlunit 22, the buffer adjustment unit 23, and the packet control unit 24.

All examples and conditional language recited herein are intended forpedagogical purposes to aid the reader in understanding the inventionand the concepts contributed by the inventor to furthering the art, andare to be construed as being without limitation to such specificallyrecited examples and conditions, nor does the organization of suchexamples in the specification relate to a showing of the superiority andinferiority of the invention. Although the embodiments of the presentinvention have been described in detail, it should be understood thatthe various changes, substitutions, and alterations could be made heretowithout departing from the spirit and scope of the invention.

What is claimed is:
 1. A base station apparatus comprising: a buffercomprising a plurality of regions, wherein each region in the buffer isdesignated by one of a plurality of priorities; and a buffer controldevice connected to the buffer and including a processor configured to:acquire predetermined information regarding data communication betweenthe base station apparatus and external apparatuses other than the basestation apparatus; predict a first amount of traffic in the datacommunication based on the acquired predetermined information; determinean occupancy ratio for the plurality of regions in the buffer based onthe predicted first amount of traffic in the data communication; andstore by the buffer in a respective designated region, in accordancewith the determined occupancy ratio, first pieces of data each of whichis assigned one of the plurality of priorities and transmitted withinthe base station apparatus from a first processing unit to a secondprocessing unit via a high speed serial interface; wherein the occupancyratio represents a relationship between a storage capacity of one of theplurality of regions in the buffer to each storage capacity of remainingplurality of regions in the buffer.
 2. The base station apparatus ofclaim 1, wherein the processor is further configured to, when it ispredicted that a second amount of traffic for second pieces of datahaving a predetermined priority increases to a threshold value or more,increase an occupancy ratio of a region of the buffer, in which thesecond pieces of data are to be stored, to a adjusted ratio.
 3. The basestation apparatus of claim 1, wherein the processor is furtherconfigured to predict that a second amount of traffic for second piecesof data having a high priority increases to a predetermined value ormore when a number of the external apparatuses that request the datacommunication from the base station apparatus becomes a predeterminednumber or more; and the processor is further configured to increase anoccupancy ratio of a region of the buffer allocated to the second piecesof data having the high priority, to a adjusted ratio when it ispredicted that the second amount of traffic increases to thepredetermined value or more.
 4. The base station apparatus of claim 1,wherein the processor is further configured to predict that, among high,middle, and low priorities, a second amount of traffic for second piecesof data having the middle priority increases to a predetermined value ormore when an amount of retransmission of the external apparatusesperforming the data communication becomes a predetermined number ofpackets or more; and the processor is further configured to make aregion allocated to the second pieces of data having the middlepriority, larger than regions of other priorities in the buffer when itis predicted that the second amount of traffic increases to thepredetermined number of packets or more.
 5. The base station apparatusof claim 1, wherein the plurality of priorities includes a firstpriority and a second priority lower than the first priority, the firstamount is amount of a first traffic that has the first priority, thefirst amount of the first traffic being predicted based on a number ofthe wireless terminals that request the data communication with the basestation apparatus, the processor is configured to predict a secondamount of a second traffic that has the second priority in the datacommunication based on the acquired predetermined information, thesecond amount of the second traffic being predicted based on an amountof retransmission of the data communication between the base stationapparatus and the wireless terminals, and the occupancy ratio for theplurality of regions in the buffer is determined based on the predictedfirst amount of the first traffic and the predicted second amount of thesecond traffic in the data communication.
 6. A buffer control methodcomprising: determining a plurality of regions in a buffer, wherein eachregion in the buffer is designated by one of a plurality of priorities;acquiring predetermined information regarding data communication betweena base station apparatus and external apparatuses other than the basestation apparatus; predicting an amount of traffic in the datacommunication based on the acquired predetermined information;determining an occupancy ratio for the plurality of regions in thebuffer based on the predicted amount of traffic in the datacommunication; storing in a respective designated region, in accordancewith the determined occupancy ratio, pieces of data each of which isassigned one of the plurality of priorities and transmitted within thebase station apparatus from a first processing unit to a secondprocessing unit via a high speed serial interface; wherein the occupancyratio represents a relationship between a storage capacity of one of theplurality of regions in the buffer to each storage capacity of remainingplurality of regions in the buffer.
 7. A base station apparatuscomprising: a buffer comprising a plurality of regions, wherein eachregion in the buffer is designated by one of a plurality of priorities;a memory; and a processor coupled to the memory and configured to: storepieces of data each of which is assigned one of the plurality ofpriorities and transmitted within the base station apparatus from afirst processing unit to a second processing unit via a high speedserial interface, in the buffer including regions each associated withone of the plurality of priorities; read out the pieces of data from thebuffer and to transmit the pieces of data to the second processing unitvia the high speed serial interface; predict an amount of traffic ofdata communication between the base station apparatus and externalapparatuses other than the base station apparatus, based onpredetermined information regarding the data communication; anddetermine an occupancy ratio for each of the regions in the buffer,based on the amount of traffic in the data communication predicted;wherein the occupancy ratio represents a relationship between a storagecapacity of one of the plurality of regions in the buffer to eachstorage capacity of remaining plurality of regions in the buffer.